1. Technical Field
The present invention relates to an offset compensation apparatus for a magnetic detection circuit and a method thereof.
2. Description of the Related Art
In a magnetic detection circuit using a Hall element, when a current is applied between any pair of counter electrodes among electrodes formed at four corners of the Hall element and a magnet is let to approach, a potential difference is made between the other remaining counter electrodes to which a current is not applied, thereby detecting magnetism.
However, the majority of Hall elements are fabricated to be non-uniform, so, although a magnet is not let to approach, a potential difference is made between the other remaining counter electrodes to which a current is not applied, resulting in that magnetism is erroneously detected as if there was a magnet nearby.
A magnetic charge detected although a magnet is not let to approach is called a magnetic offset, and an offset compensation apparatus of a magnetic detection circuit is employed to compensate for such a magnetic offset.
The prior art offset compensation apparatus of a magnetic detection circuit is configured to amplify a magnetic offset through an amplifying unit by using a spinning current scheme, sample the amplified magnetic offset through a sample hold circuit unit and hole it, and then, cancel (or remove) an offset through an adding unit.
However, in the prior art, since the magnetic offset is amplified through the amplifying unit, the offset can be canceled only within a range in which the offset is not saturated through a gain of the amplifying unit, causing a problem in which an operating point is distorted at a region beyond (or outside) the range.